Regulatory Module Network of Basic/Helix-loop-helix Transcription Factors During Bovine Preimplantation Development in vivo

The basic/helix-loop-helix (bHLH) proteins are important components of the transcriptional regulatory network, play pivotal roles in embryonic development. In order to understand the regulatory mechanisms of bHLH Transcription factors (TFs) in developing bovine embryos, we inferred their regulatory network from genome-wide gene expression profiles with the module networks method. A regulatory network comprising 12 important bHLH TFs and 357 target genes was constructed. The network was divided into 25 modules based on expression profiles. In addition, 18 cooperative bHLH TF pairs were also detected in the network. This cooperation suggests possible regulation between TFs. Interestingly, lots of TFs in the network regulate more than one module. A novel cross-repression between ID3 and HEYL was identified, which may control various functions in different developing stages. Our network will help in the analysis of mechanisms underlying embryonic losses and for improving in vitro culture systems.